1. A method of sampling an unknown clock signal using a known clock signal, comprising:
forming from the unknown clock signal a derived clock signal;
forming a sequence of multiple delayed versions of the derived clock signal, each delayed version following a first delayed version in the sequence being delayed more than a previous delayed version in the sequence;
for each delayed version of the derived clock signal:
sampling the delayed version of the derived clock signal at successive times defined by the known clock signal to produce first intermediate values; and
performing transition detection using the first intermediate values to produce second intermediate values; and
combining the second intermediate values produced from the delayed versions of the derived clock signal to produce sample values.
2. The method of claim 1, wherein combining comprises summing the second intermediate values.
3. The method of claim 2, wherein combining comprises mapping a sum of the second intermediate values to a smaller number of values.
4. The method of claim 3, wherein mapping is performed in accordance with an anticipated frequency range of the unknown clock signal.
5. A circuit for sampling an unknown clock signal using a known clock signal, comprising:
circuitry for deriving from the unknown clock signal a derived clock signal;
a delay chain of logic elements, coupled to the derived clock signal and the unknown clock signal, for forming a sequence of multiple delayed versions of the derived clock signal, each delayed version following a first delayed version in the sequence being delayed more than a previous delayed version in the sequence;
multiple sampling chains of logic elements, each sampling chain coupled to one of the multiple delayed versions of the derived clock signal and to the known clock signal;
multiple transition detection circuits, each coupled to one of the sampling chains such that, for each time a logic level of a delayed version of the derived clock signal is different at successive sampling times of the known clock signal, a transition detection circuit produces as an output signal thereof a transition indication value; and
a combining circuit for logically combining output signals of the transition detection circuits.
6. The apparatus of claim 5, wherein the combining circuit comprises a summation element for forming a sum of transition values and decision logic for comparing the sum to a threshold value.
7. The apparatus of claim 6, wherein the threshold value is set in accordance with an anticipated frequency range of the unknown clock signal.
8. A method of forming a number stream representing frequency or phase of digital or digitized clock signals using a digital circuit, one of the clock signals being a known clock signal and another of the clock signals being an unknown clock signal, comprising:
applying to the digital circuit an alias value indicating an expected frequency range of a received unknown clock signal; and
forming the number stream in accordance with the alias value, said number stream representing the frequency or phase of the unknown clock signal.
9. A digital circuit for forming a number stream representing frequency or phase of an unknown clock signal, comprising:
a first logic section including multiple chains of flip flops, each chain producing an intermediate value for each period of a known clock signal; and
a second logic section configured to receive an alias value indicating an expected frequency range of the unknown clock signal and, in successive cycles of the known clock signal, operable to compare the alias value to sums of the intermediate values produced by said multiple chain of flip-flops to form the number stream.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A notebook computer with attached wrist support, the notebook computer comprising: a computer body having a top panel, a keyboard, and a pointing device; and the wrist support being attached to the top panel of the notebook computer whereby the wrist support does not interfere with the operation of the keyboard or pointing device, wherein the wrist support is compressible and comprises a base having one or more flat surfaces the largest of the flat surfaces having a surface area of less than 60 cm2 and a hook and loop type connector for attaching the wrist support to the top panel of the notebook computer.
2. The notebook computer of claim 1, wherein the notebook computer further comprises a video display and the notebook computer is reversibly configurable between a closed position wherein the video display is positioned immediately on top of the top panel, and an open position wherein the video display is positioned not immediately on top of the top panel, wherein the wrist support is sufficiently compressible that the notebook computer can be placed in the closed position with the wrist support attached to the top panel.
3. The notebook computer of claim 1, wherein the wrist support comprises a compressible material.
4. The notebook computer of claim 3, wherein the compressible material is synthetic sponge.
5. The notebook computer of claim 1, wherein the wrist support consists essentially of the base and the base comprises a compressible material.
6. The notebook computer of claim 5, wherein the compressible material is synthetic sponge.
7. A notebook computer with two attached wrist supports, the notebook computer comprising: a computer body having a top panel, a video display, a keyboard, and a pointing device; and a first wrist support being attached to the right side of the top panel of the notebook computer and a second wrist support being attached to the left side of the top panel of the notebook computer, whereby the wrist supports do not interfere with the operation of the keyboard or pointing device,
wherein the wrist supports are each compressible, and comprise a base having one or more flat surfaces the largest of the flat surfaces having a surface area of less than 60 cm2 and a means for attaching each wrist support to the top panel of the notebook computer,
and wherein the notebook computer is reversibly configurable between a closed position wherein the video display is positioned immediately on top of the top panel, and an open position wherein the video display is positioned not immediately on to of the top panel, and the wrist supports are sufficiently compressible so that the notebook computer can be placed in the closed position with the wrist supports attached to the top panel.
8. The notebook computer of claim 7, wherein the means for attaching the wrist supports to the top panel of the notebook computer comprises a hook and loop type connector.
9. The notebook computer of claim 7, wherein the means for attaching to the wrist supports to the top panel of the notebook computer comprises an adhesive tape.
10. The notebook computer of claim 9, wherein the wrist supports each comprise a bottom part and the adhesive tape is attached to the bottom part of the wrist supports.
11. The notebook computer of claim 7, wherein the wrist supports each comprise a compressible material.
12. The notebook computer of claim 11, wherein the compressible material is synthetic sponge.
13. The notebook computer of claim 7, wherein the wrist supports consist essentially of the bases and the bases comprises a compressible material.
14. The notebook computer of claim 13, wherein the compressible material is synthetic sponge.
15. The notebook computer of claim 7, wherein the means for attaching to the wrist supports to the top panel of the notebook computer comprise an adhesive tape attached to the bottom part of the wrist supports and the wrist supports comprise a compressible material comprising synthetic sponge.